Method of changing the composition of iron and steel.



' BI METHOD OF CHANGINQTHE COMPOSITION-0F IRON AND STEEL. APPLICATION FILED APR. 13.1905- Llfififi'wo Patented 00 5.12, 19 5.

' pally in section, and Fig. 2 is a similar view.

To all cvhom it may concern:

- nnir earns A'rnn Prion.

BRUCE FORD, or PHILADELPHIA, P NNSYLVANIA.

METHOD OF CHANGING COMPOSITION OF IRON ANDSTEEL.

Specification of Iletters Patent. I Patented Oct. 12, 1915.

Application filed April 13, 1905. Serial No. 255,359.

' is a specification;

Case hardening orthe carbureting of-a mere surface skin has been accomplished by electrically or otherwise heating the metal and while hot rubbing the surface With a suitable steelifying material, such as potassium cyanid. This can be quickly accom-' plished, but it results in the production of a mere superficial film.

The principal object of the present in vention is to provide an expeditious method for accurately controlling or changing the carbon contents and hardening constituents ofiron and steel throughout the mass or to a substantial depth;

To this' and other endshereinafter set forth'the invention comprises the improvements to be presently described and finally claimed.

The drawings illustrate types of appar ratus which may be used for the practice of the process of the invention and in them Figure 1,. is a diagrammatic view princi- To practise the process of the invention the metal is immersed in a suitable carbureting medium and while permitted to remain or stay therein, is electrically heated in such a way that its body or mass is molten, and the metal remains exposed to these conditions until the composition of the whole of it is changed or until its composition is changed to a substantial depth which is a matter of, comparatively, a very short time, measurable inminutes or hours as distinguished from hours. and days or even weeks. The temperature to which the body or mass of metalis heated can be accu-= rately controlled and regulated during the entire period of time in which the metal, remains immersed in orexposed to the medium.

- For the sake of a further description-an explanation of the method. as practised in the apparatus shown willnow be given.

A,,is areceptacle as of castiron preferably fitted with a removable cover B. Conductor bars C and 0 lead into the recepas shown.

tacle A, but are insulated therefrom by the bushings D. Within the receptacle is the medium E, which may be either gas, vapor,

' liquid, or a granular or powdered mass.-

F F are contact pieces for the conductorsC, C and between these there is an open receptacle P, of fire-clay or other-suitable refractofy substances in which the metal may be allowed to melt without breaking the continuity of the .electric circuit. If

the mediuInE is a gas or vapor it may be allowed \to circulate'by means of the inlet and outlet pipes K, K The efl'ect'of this electric'current' is 'to heat to 1 melting the mass or body of the'metal G, whereupon it 1 absorbs carbon or other hardeningconstituents from the'medium in the manner described. 'Obviously the receptacle A, is not heated and therefore it is not affected, so

- that all of the constituents of the medium and all of'the heat are available to the metal under treatment, the cover B being clamped For the sake-ofa further explanation it may be stated that for each square inch of cross-section of the metal to be treated there is required approximately 2,000 to 10,000 amperes andfor each foot y in length of the "metal to be treated there is required fromotwo to five volts according to the shapeof its crossrsection and the capacity of the medium for taking'away heat.

In connection with the practice of'the in= vention by me'ansof the apparatus illus trated 1n.F 1g. 2, the metal to be treated is] contained in an openreceptacle mounted" in the receptacle A. This receptacle is made] of some suitable material as graphite andis shown as connected to the terminal Ftand conductor C A suitable pole piece '8', as of carbon is connected to the contact F, ofconductolr C, in such'a way that an arc can be formed between the pol'eipiece F and the metal G. In the constructionshown, the contact F, is a hinged member pivoted at a,

and the arc is made and adjusted by means of therod and hand-wheel b, and c. The

result of this is-that the entire'm'ass or body .of the metal is heated fand may be melted and is therefore affected in the manner described. 4 j

As an illustration of a carbonizing medium reference may be made to the fumes of gasolene, some appropriate form of cyanogen ground carbon, lamp black, bone black. or the like, or a mixture of these or some of these.

It will be obvious .to those skilled in the art to which the invention relates that modifications may be made in details Without de--- parting from the spirit'there'of, hence the invention is not limited further thanthe prior stateof the art may require, but i Having thus described the nature and objects of my invention, what I claim as new and desire to secure by Letters Patent is: The methodiof carburizing iron and steel which consists in melting the entire mass of the metal in a chamber from which air is excluded to prevent oxisigned my name.

and liquefying give carbon to the metal absorptivel'y, and

applying electric energy to the body or mass of the metal sufficient to maintain the molten condition of. the metal and until its composition is changed by such absorptive contact.

In testimony whereof I have hereunto BRUCE .F ORD. l Vitness'es 4 G; WV. WOODWARD', EDWARD G. STEINMETZ. 

